Severe acute respiratory syndrome (SARS) caused by coronavirus is an emerging human infectious disease that epidemically spread worldwide. Therefore, the actual diagnostic method, preventing and therapeutic vaccine, and antiviral drugs are urgently demanded. This proposal aims at development of peptide-based vaccine including combinatorial synthesis of overlapped peptide library, identification of B- and T-cell epitopes directly, selection of neutralizing antigens and immunization of animal. 1.Using our coding and "MBGB" combinatorial technology, total 1938 overlapped individual peptides (10 amino acids in length) will be synthesized according to the BJ01 protein sequence including spike glycoprotein, membrane protein, envelope protein, and nucleocapasid protein, which potentially comprise the human immuno-recognizing domains of SARS CoV. 2. B-cell epitopes will be directly determined using ELISA method. The peptides reacted across with at least twelve antibody-positive sera of SARS patients will be determined as being positive. 3. SARS CoV specific T-cell epitopes from above proteins will be identified by peptide's stimulation of peripheral blood mononuclear cells (PBMC) releasing cytokines of recovered SARS patients, such as IFN-gamma, IL2, or IL12 detecting by Elispot method. 4. The elongated peptides covering two or three identified epitopes will be designed, synthesized and tested their antigenicity. Their immunogenicity will be determined when the anti-peptide (peptide-carrier conjugate) antibody from animal sera neutralizes the SARS CoV. 5. Multiple antigens containing both B-cell neutralizing antigens and SARS CoV specific T-cell epitopes will covalently conjugate onto protein carrier which will be able to immunize animals. The protection of SARS CoV challenges and CTL responses will be investigated to evaluate the peptide-based vaccine.